Step 1 Preheat oven to 180°C. Place asparagus into a small heatproof bowl. Just cover with boiling water, stand for 1 minute, then drain well.
Step 2 Place ricotta, basil, onion, lemon zest and half the asparagus into a bowl and stir until well combined. Season with ground black pepper. Cut a deep, horizontal pocket in the side of each chicken breast, being careful not to cut all the way through. Stuff each breast with a quarter of the ricotta mixture and secure with a toothpick.
Step 3 Spray a large frying pan with oil and place over high heat. Add chicken and cook for 2 minutes each side, until golden. Transfer chicken to a lined baking tray and bake for 10–12 minutes, or until cooked through.
Step 4 Meanwhile, combine tomatoes, remaining asparagus and chives in a bowl. Set aside.
Step 5 Return frying pan to high heat and spray with a little more oil. Add spinach, tossing until just wilted (about 2 minutes).
Step 6 Top chicken with tomato mixture and serve with spinach and corn cobs.